This invention relates to a vehicle window glass antenna for receiving radio broadcast waves, and more particularly to an antenna constructed of conductive strips formed on or in a vehicle window glass which is provided with defogging heater strips, such as an automobile rear window glass.
In recent automobiles there is a trend to adoption of a so-called window glass antenna for receiving broadcast waves. In most cases the window glass antenna is provided to the rear window glass and is constructed of a conductive strips disposed on the glass pane in a suitable pattern, and the antenna is located in a relatively narrow space left above an array of defogging heater strips. Usually the conductive strips used as the antenna elements are electrically independent of the heater strips as shown, for example, in U.S. Pat. No. 4,608,570.
With an automobile window glass antenna of the above described type it is possible to receive FM radio broadcast waves with fairly high gains, but it is difficult to receive AM radio broadcast waves with sufficient gains mainly because of narrowness of the space which the antenna is allowed to occupy. As a compensatory measure, it is known to make an electrical connection between the antenna strips and the heater strips to utilize the heater strips as auxiliary elements of the antenna, and vice versa. However, this measure has a disadvantage that during defogging operation intrusion of considerable noise into the received signal is inevitable.